1. Field of the Invention
The present invention relates to an image processing system for processing image information in the form of electrical signals.
2. Description of the Prior Art
There is already known image recording in response to image signals obtained by photoelectrically reading image information, or transmission of said signals to a distant location. One of the advantages of processing the image information in the form of electrical signals lies in the possibility of forming a so-called network composed of plural stations for image signals processing mutually connected through transmission channels, thus enabling arbitrary signal transmission among said stations
Such a system is, however, associated with a drawback that, during signal transmission between certain stations, other stations are not available for the transmission of information. For example, a facile copying operation is difficult to achieve when an original reading unit and a printer unit belonging to the system are used as a copying apparatus.
Also, such system is provided with a control unit for controlling the system, and the image information is transmitted through said control unit at the image processing. However, the transmission of the image signals through the control unit is unnecessary and is sometimes disadvantageous in terms of speed and control of the processing in case a simple copying operation is desired.
Besides, such image processing system as described above may receive image information from various sources other than the aforementioned original reading unit, such as a magnetic disk, a communication unit or a microfilm file for photoelectrically reading microfilms. These image information sources have different transfer rates of the image information. For example, the original reading unit utilizing a CCD image sensor of ca. 5,000 bits for reading an A3 sized original image has an output transfer rate of 18 MHz, while a microfilm file utilizing a relatively small CCD image sensor of ca. 3,600 bits matching the image size has an output transfer rate of 8 MHz. In consideration of the cost and space, the image processing apparatus should preferably be capable of adapting to all such sources of different transfer rates, but the wiring becomes complicated and costly if separate signal lines are required for each image information source to be connected.
Besides, in case of reading, for example, a document with a scanner and storing the obtained electrical signals into a memory unit such as an optical disk file, by means of a conventional system in which the reading start signal is released from a keyboard of a control unit or a work station, the operator is required to manipulate the keyboard of the work station after the document is placed on the scanner. This inconvenience of manipulating two terminals is particularly marked in case the apparatus lacks an automatic original feeder or in case of handling bound originals.